CERN Yellow Reports: Conference Proceedings, Vol 2 (2018): Proceedings of "Tracking Collimation" ICFA Workshop

MERLIN is an accelerator physics library written in C++ which can be used for a range of accelerator tracking simulations, including collimation in hadron colliders. Recently MERLIN has been upgraded to provide a robust tool for HL-LHC collimation, including the treatment of composite materials, and a hollow electron lens process. We describe the features of MERLIN used in collimation simulations.